Question

A classroom is 7m long, 6.5m wide and 4m high. It has one door 3m X 1.4m and 3 windows each measuring 2m X 1m. The interior walls are to be colour washed. The contractor charges Rs. 5.25 per sq.m. Find the cost of colour washing.​

Answer 1

Answer:

here is ur answer

Step-by-step explanation:

area of classroom (cuboid) = l×b×h

= 7×6.5×4

= 182 m²

area of door =3×1.4×3

= 12.6m²

area of window= 2×1= 2m²

area of 3 window =2×3= 6m²

area of color washing = area of classroom - area of door and area of 3 windows

= 182-12.6-6 m² = 163.4 m²

cost of washing = 163.4×5.25

= 857.85 RS.

hope it will help you plz mark me as branliest

Answer 2

${\underline{\underline{\bf{Given:}}}}$

• That, a classroom has a door and 3 windows. The interior walls of the classroom are to be colour washed.
• Dimensions of the classroom: Length = 7 metres, breadth = 6.5 metres and height = 4 metres.
• Dimensions of the door: Length = 3 metres and breadth = 1.4 metres.
• Dimensions of a window: Length = 2 metres and breadth = 1 metre.
• The cost of colour washing per m² = 5.25/-

${\underline{\underline{\bf{Need\:to\:find:}}}}$

• The cost of colour washing.

${\underline{\underline{\bf{Formulae\:to\:be\:used:}}}}$

$\underline{\boxed{\sf{{Area}_{(Rectangle)}=lb\:sq.units}}}$

$\underline{\boxed{\sf{{LSA}_{(Cuboid)}=2h(l+b)\:sq.units}}}$

${\underline{\underline{\bf{Solution:}}}}$

First, the area of walls to be colour washed should be found to find the cost of colour washing. We know that, a room has 4 walls. So, the formula of LSA of cuboid should be applied. It is also given that, there are 3 windows and a door in the classroom. These cannot be painted. So, we should find the area of windows and door, and then subtract it from the LSA of classroom. Finally, multiplying the area obtained with cost per m² gives the required answer.

Area of the door:

$\:\:\:\:\:\:\:\implies{\sf{lb\:sq.units}}$

$\:\:\:\:\:\:\:\implies{\sf{3\times 1.4}}$

$\:\:\:\:\:\:\:\implies{\underline{\underline{\sf{4.2\:{m}^{2}}}}}$

Area of windows:

$\:\:\:\:\:\:\:\implies{\sf{lb\:sq.units}}$

$\:\:\:\:\:\:\:\implies{\sf{2\times 1}}$

$\:\:\:\:\:\:\:\implies{\sf{2\:{m}^{2}}}$

There are three windows. So,

$\rightarrow{\sf{3\times Area\:of\:a\:window}}$

$\rightarrow{\sf{3\times 2}}$

$\rightarrow{\underline{\underline{\sf{6\:{m}^{2}}}}}$

Area of 4 walls:

By applying the formula of LSA of cuboid,

$\:\:\:\:\:\:\:\implies{\sf{2h(l+b)\:sq.units}}$

$\:\:\:\:\:\:\:\implies{\sf{2\times 4\times (7+6.5)}}$

$\:\:\:\:\:\:\:\implies{\sf{2\times 4\times 13.5}}$

$\:\:\:\:\:\:\:\implies{\sf{8\times 13.5}}$

$\:\:\:\:\:\:\:\implies{\underline{\underline{\sf{108\:{m}^{2}}}}}$

Area of walls, excluding door and windows:

$\rightarrow$ Area of 4 walls - (Area of door + Area of windows)

$\rightarrow{\sf{108-(4.2+6)}}$

$\rightarrow{\sf{108-10.2}}$

$\rightarrow{\underline{\underline{\sf{97.8\:{m}^{2}}}}}$

★ Cost of colour washing:

$\rightarrow$ Area of walls (excluding door and windows) × Cost per m²

$\rightarrow{\sf{97.8\times 5.25}}$

$\rightarrow{\underline{\underline{\sf{\red{513.45/-}}}}}$

${\underline{\underline{\bf{Final\:answer:}}}}$

• The cost of colour washing the classroom is 513.45/-.

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